Fungicidal mixtures for combating rice pathogens

ABSTRACT

Fungicidal mixtures for controlling rice pathogens, comprising, as active components, 
 
1) the triazolopyrimidine derivative of the formula I,  
                 
and 
 
2) an acryloylmorpholide of the formula II,  
                 
in which X is chlorine or fluorine, in a synergistically effective amount, methods for controlling rice pathogens using mixtures of the compound I with the compounds II, the use of the compound I and the compounds II for preparing such mixtures and compositions comprising these mixtures are described.

The present invention relates to fungicidal mixtures for controllingrice pathogens, comprising as active components1) the triazolopyrimidine derivative of the formula I,

and2) an acryloylmorpholide of the formula II,

in which X is chlorine or fluorinein a synergistically effective amount.

Moreover, the invention relates to a method for controlling ricepathogens using mixtures of the compound I with the compounds II and tothe use of the compound I with the compounds II for preparing suchmixtures and compositions comprising these mixtures.

The compound I,5-chloro-7-(4-methylpiperidin-1-yl)-6-(2,4,6-trifluorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidine,its preparation and its action against harmful fungi are known from theliterature (WO 98/46607).

The compounds II, their preparation and their action against harmfulfungi are likewise known from the literature (EP-A 120 321). Thecompound II in which X is chlorine,3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)-1-morpholin-4-ylpropenone(IIa), is, under the common name “dimethomorph”, a long-establishedfungicide used against Oomycetes in the cultivation of potatoes andvegetables. The compound II in which X is fluorine,3-(4-fluorophenyl)-3-(3,4-dimethoxyphenyl)-1-morpholin-4-ylpropenone(IIb), is, under the common name “flumorph”, likewise known (EP-A 860438). Compounds IIa and IIb are present as E,Z isomer mixtures.

Mixtures of triazolopyrimidine derivatives with dimethomorph are knownin a general manner from EP-A 988 790. The compound I is embraced by thegeneral disclosure of this publication, but not explicitly mentioned.Accordingly, the combination of compound I with the compounds II isnovel.

The synergistic mixtures known from EP-A 988 790 are described as beingfungicidally active against various diseases of cereal, fruit andvegetable, in particular mildew on wheat and barley or gray mold onapples.

Owing to the special cultivation conditions of rice plants, therequirements that a rice fungicide has to meet are considerablydifferent than those that fungicides used in cereal or fruit growinghave to meet. There are significant differences in the applicationmethod: in rice crops, the fungicide is usually applied directly ontothe soil during or shortly after sowing. The fungicide is taken up intothe plant via the roots and transported in the sap of the plant to theplant parts to be protected. For rice fungicides, high systemic actionis therefore essential. In contrast, in cereal or fruit growing, thefungicide is usually applied onto the leaves or the fruits; accordingly,in these crops the systemic action of the active compounds isconsiderably less important.

Moreover, rice pathogens are typically different from those in cereal orfruit. Pyricularia oryzae and Corticium sasakii (syn. Rhizoctoniasolani) are the pathogens of the diseases most prevalent in rice plants.Rhizoctonia solani is the only pathogen of agricultural significancefrom the sub-class Agaricomycetidae. In contrast to most other fungi,this fungus attacks the plants not via spores but via a myceliuminfection.

For these reasons, findings concerning the fungicidal activity of activecompounds in the cultivation of cereals or fruit cannot be transferredto rice crops.

It was an object of the present invention to provide, with a view to aneffective control of rice pathogens at application rates which are aslow as possible, mixtures which, at a reduced total amount of activecompounds, have improved action against the harmful fungi.

We have found that this object is achieved by the mixtures defined atthe outset. Surprisingly, it has been found that the mixtures defined atthe outset allow considerably better control of rice pathogens than thedimethomorph mixtures disclosed in EP-A 988 790. Moreover, we have foundthat simultaneous, that is joint or separate, application of thecompounds I and the compounds II or successive application of thecompounds I and the compounds II allows better control of rice pathogensthan is possible with the individual compounds.

When preparing the mixtures, it is preferred to employ the pure activecompounds I and IIa or IIb, to which further active compounds againstharmful fungi or other pests, such as insects, arachnids or nematodes,or else herbicidal or growth-regulating active compounds or fertilizerscan be added.

Further suitable active compounds in the above sense are, in particular,fungicides selected from the following group:

-   -   acylalanines, such as benalaxyl, metalaxyl, ofurace or oxadixyl,    -   amine derivatives, such as aldimorph, dodine, dodemorph,        fenpropimorph, fenpropidin, guazatine, iminoctadine, spiroxamine        or tridemorph,    -   anilinopyrimidines, such as pyrimethanil, mepanipyrim or        cyprodinyl,    -   antibiotics, such as cycloheximide, griseofulvin, kasugamycin,        natamycin, polyoxin or streptomycin,    -   azoles, such as bitertanol, bromoconazole, cyproconazole,        difenoconazole, dinitroconazole, epoxiconazole, fenbuconazole,        fluquiconazole, flusilazole, flutriafol, hexaconazole, imazalil,        ipconazole, metconazole, myclobutanil, penconazole,        propiconazole, prochloraz, prothioconazole, simeconazole,        tebuconazole, tetraconazole, triadimefon, triadimenol,        triflumizole or triticonazole,    -   dicarboximides, such as iprodione, myclozolin, procymidone or        vinclozolin,    -   dithiocarbamates, such as ferbam, nabam, maneb, mancozeb, metam,        metiram, propineb, polycarbamate, thiram, ziram or zineb,    -   heterocyclic compounds, such as anilazine, benomyl, boscalid,        carbendazim, carboxin, oxycarboxin, cyazofamid, dazomet,        dithianon, famoxadone, fenamidone, fenarimol, fuberidazole,        flutolanil, furametpyr, isoprothiolane, KIF 230, mepronil,        nuarimol, picobenzamid, probenazole, proquinazid, pyrifenox,        pyroquilon, quinoxyfen, silthiofam, thiabendazole, thifluzamide,        thiophanate-methyl, tiadinil, tricyclazole or triforine,    -   copper fungicides, such as Bordeaux mixture, copper oxychloride,        copper hydroxide, copper oxide, (basic) copper sulfate, copper        oxychloride sulfate,    -   nitrophenyl derivatives, such as binapacryl, dinocap, dinobuton        or nitrophthalisopropyl,    -   phenylpyrroles, such as fenpiclonil or fludioxonil,    -   sulfur,    -   other fungicides, such as acibenzolar-S-methyl, benthiavalicarb,        carpropamid, chlorothalonil, cyflufenamid, cymoxanil, dazomet,        diclomezine, diclocymet, diethofencarb, edifenphos, ethaboxam,        fenhexamid, fentin acetate, fenoxanil, ferimzone, fluazinam,        fosetyl, fosetyl-aluminum, iprovalicarb, hexachlorobenzene,        metrafenone, pencycuron, propamocarb, phthalide,        tolclofos-methyl, quintozene or zoxamide,    -   strobilurins, such as azoxystrobin, dimoxystrobin,        fluoxastrobin, kresoxim-methyl, metominostrobin, orysastrobin,        picoxystrobin, pyraclostrobin or trifloxystrobin,    -   sulfenic acid derivatives, such as captafol, captan,        dichlofluanid, folpet or tolylfluanid,    -   cinnamides and analogous compounds, such as flumetover.

In one embodiment of the mixtures according to the invention, thecompounds I and II are admixed with a further fungicide III or twofungicides III and IV.

Suitable components III and, if appropriate, IV from this list are inparticular the strobilurins, dithiocarbamates, copper fungicides and theother fungicides mentioned.

Preference is given to mixtures of the compounds I and II with onecomponent III.

Particular preference is given to mixtures of the compounds I and II.

Especially preferred are mixtures of the compound I with dimethomorph(IIa).

The mixtures of compounds I and IIa or IIb, or the compounds I and IIaor IIb used simultaneously, that is jointly or separately, exhibitoutstanding action against rice pathogens from the classes of theAscomycetes, Deuteromycetes and Basidiomycetes. They have high systemicaction and can therefore be used for the treatment of seed and asfoliar- and soil-acting fungicides.

They are especially important for controlling harmful fungi on riceplants and their seeds, such as Bipolaris and Drechslera species, andalso Pyricularia oryzae. They are particularly suitable for controllingrice blast caused by Pyricularia oryzae.

In addition, the combination according to the invention of the compoundsI and II is also suitable for controlling other pathogens, such as, forexample, Septoria and Puccinia species in cereals and Alternaria andBoytritis species in vegetables, fruit and grapevine.

The compounds I and the compounds IIa or IIb can be appliedsimultaneously, that is jointly or separately, or in succession, thesequence, in the case of separate application, generally not having anyeffect on the result of the control measures.

The compound I and the compounds II are usually applied in a weightratio of from 100:1 to 1:100, preferably from 20:1 to 1:20, inparticular from 10:1 to 1:10.

The components III and, if appropriate, IV are, if desired, mixed withthe compound I in a ratio of from 20:1 to 1:20.

Depending on the desired effect, the application rates of the mixturesaccording to the invention are from 5 g/ha to 1500 g/ha, preferably from50 to 1000 g/ha, in particular from 50 to 750 g/ha.

Correspondingly, the application rates of the compound I are generallyfrom 1 to 1000 g/ha, preferably from 10 to 750 g/ha, in particular from20 to 500 g/ha.

Correspondingly, the application rates of the compound II are generallyfrom 1 to 1000 g/ha, preferably from 10 to 750 g/ha, in particular from20 to 500 g/ha.

In the treatment of seed, the application rates of the mixture aregenerally from 1 to 1000 g/100 kg of seed, preferably from 1 to 200g/100 kg, in particular from 5 to 100 g/100 kg.

In the control of harmful fungi which are pathogenic to rice plants, theseparate or joint application of the compounds I and II or of themixtures of the compounds I and II is carried out by spraying or dustingthe seeds, the seedlings, the plants or the soils before or after sowingof the plants or before or after emergence of the plants. The compoundsare preferably applied jointly or separately, preferably by applyinggranules or by dusting the soils.

The mixtures according to the invention or the compounds I and II can beconverted into the customary formulations, for example solutions,emulsions, suspensions, dusts, powders, pastes and granules. Theapplication form depends on the particular purpose; in each case, itshould ensure a fine and uniform distribution of the compound accordingto the invention.

The formulations are prepared in a known manner, for example byextending the active compound with solvents and/or carriers, if desiredusing emulsifiers and dispersants. Solvents/auxiliaries which aresuitable are essentially:

-   -   water, aromatic solvents (for example Solvesso products,        xylene), paraffins (for example mineral oil fractions), alcohols        (for example methanol, butanol, pentanol, benzyl alcohol),        ketones (for example cyclohexanone, gamma-butyrolactone),        pyrrolidones (NMP, NOP), acetates (glycol diacetate), glycols,        fatty acid dimethylamides, fatty acids and fatty acid esters. In        principle, solvent mixtures may also be used.    -   carriers such as ground natural minerals (for example kaolins,        clays, talc, chalk) and ground synthetic minerals (for example        highly disperse silica, silicates); emulsifiers such as nonionic        and anionic emulsifiers (for example polyoxyethylene fatty        alcohol ethers, alkylsulfonates and arylsulfonates) and        dispersants such as lignin-sulfite waste liquors and        methylcellulose.

Suitable surfactants are alkali metal, alkaline earth metal and ammoniumsalts of lignosulfonic acid, naphthalenesulfonic acid, phenolsulfonicacid, dibutylnaphthalenesulfonic acid, alkylarylsulfonates, alkylsulfates, alkylsulfonates, fatty alcohol sulfates, fatty acids andsulfated fatty alcohol glycol ethers, furthermore condensates ofsulfonated naphthalene and naphthalene derivatives with formaldehyde,condensates of naphthalene or of naphthalenesulfonic acid with phenoland formaldehyde, polyoxyethylene octylphenyl ether, ethoxylatedisooctylphenol, octylphenol, nonylphenol, alkylphenyl polyglycol ethers,tributylphenyl polyglycol ether, tristearylphenyl polyglycol ether,alkylaryl polyether alcohols, alcohol and fatty alcohol/ethylene oxidecondensates, ethoxylated castor oil, polyoxyethylene alkyl ethers,ethoxylated polyoxypropylene, lauryl alcohol polyglycol ether acetal,sorbitol esters, lignin-sulfite waste liquors and methylcellulose.

Substances which are suitable for the preparation of directly sprayablesolutions, emulsions, pastes or oil dispersions are mineral oilfractions of medium to high boiling point, such as kerosene or dieseloil, furthermore coal tar oils and oils of vegetable or animal origin,aliphatic, cyclic and aromatic hydrocarbons, for example toluene,xylene, paraffin, tetrahydronaphthalene, alkylated naphthalenes or theirderivatives, methanol, ethanol, propanol, butanol, cyclohexanol,cyclohexanone, isophorone, strongly polar solvents, for example dimethylsulfoxide, N-methylpyrrolidone and water.

Powders, materials for spreading and dustable products can be preparedby mixing or concomitantly grinding the active substances with a solidcarrier.

Granules, for example coated granules, impregnated granules andhomogeneous granules, can be prepared by binding the active compounds tosolid carriers. Examples of solid carriers are mineral earths such assilica gels, silicates, talc, kaolin, attaclay, limestone, lime, chalk,bole, loess, clay, dolomite, diatomaceous earth, calcium sulfate,magnesium sulfate, magnesium oxide, ground synthetic materials,fertilizers, such as, for example, ammonium sulfate, ammonium phosphate,ammonium nitrate, ureas, and products of vegetable origin, such ascereal meal, tree bark meal, wood meal and nutshell meal, cellulosepowders and other solid carriers.

In general, the formulations comprise from 0.01 to 95% by weight,preferably from 0.1 to 90% by weight, of the active compounds. Theactive compounds are employed in a purity of from 90% to 100%,preferably 95% to 100% (according to NMR spectrum).

The following are examples of formulations: 1. Products for dilutionwith water

A) Soluble Concentrates (SL)

10 parts by weight of the active compounds are dissolved in water or ina water-soluble solvent. As an alternative, wetters or other auxiliariesare added. The active compound dissolves upon dilution with water.

B) Dispersible Concentrates (DC)

20 parts by weight of the active compounds are dissolved incyclohexanone with addition of a dispersant, for examplepolyvinylpyrrolidone. Dilution with water gives a dispersion.

C) Emulsifiable Concentrates (EC)

15 parts by weight of the active compounds are dissolved in xylene withaddition of calcium dodecylbenzenesulfonate and castor oil ethoxylate(in each case 5% strength). Dilution with water gives an emulsion.

D) Emulsions (EW, EO)

40 parts by weight of the active compounds are dissolved in xylene withaddition of calcium dodecylbenzenesulfonate and castor oil ethoxylate(in each case 5% strength). This mixture is introduced into water bymeans of an emulsifier (Ultraturax) and made into a homogeneousemulsion. Dilution with water gives an emulsion.

E) Suspensions (SC, OD)

In an agitated ball mill, 20 parts by weight of the active compounds arecomminuted with addition of dispersants, wetters and water or an organicsolvent to give a fine active compound suspension. Dilution with watergives a stable suspension of the active compound.

F) Water-Dispersible Granules and Water-Soluble Granules (WG, SG)

50 parts by weight of the active compounds are ground finely withaddition of dispersants and wetters and made into water-dispersible orwater-soluble granules by means of technical appliances (for exampleextrusion, spray tower, fluidized bed). Dilution with water gives astable dispersion or solution of the active compound.

G) Water-Dispersible Powders and Water-Soluble Powders (WP, SP)

75 parts by weight of the active compounds are ground in a rotor-statormill with addition of dispersants, wetters and silica gel. Dilution withwater gives a stable dispersion or solution of the active compound.

2. Products to be Applied Neat

H) Dustable Powders (DP)

5 parts by weight of the active compounds are ground finely and mixedintimately with 95% of finely divided kaolin. This gives a dustableproduct.

I) Granules (GR, FG, GG, MG)

0.5 part by weight of the active compounds is ground finely andassociated with 95.5% carriers. Current methods are extrusion,spray-drying or the fluidized bed. This gives granules to be appliedneat.

J) ULV Solutions (UL)

10 parts by weight of the active compounds are dissolved in an organicsolvent, for example xylene. This gives a product to be applied neat.

The active compounds can be used as such, in the form of theirformulations or the use forms prepared therefrom, for example in theform of directly sprayable solutions, powders, suspensions ordispersions, emulsions, oil dispersions, pastes, dustable products,materials for spreading, or granules, by means of spraying, atomizing,dusting, spreading or pouring. The use forms depend entirely on theintended purposes; it is intended to ensure in each case the finestpossible distribution of the active compounds according to theinvention.

Aqueous use forms can be prepared from emulsion concentrates, pastes orwettable powders (sprayable powders, oil dispersions) by adding water.To prepare emulsions, pastes or oil dispersions, the substances, as suchor dissolved in an oil or solvent, can be homogenized in water by meansof a wetter, tackifier, dispersant or emulsifier. Alternatively, it ispossible to prepare concentrates composed of active substance, wetter,tackifier, dispersant or emulsifier and, if appropriate, solvent or oil,and such concentrates are suitable for dilution with water.

The active compound concentrations in the ready-to-use preparations canbe varied within relatively wide ranges. In general, they are from0.0001 to 10%, preferably from 0.01 to 1%.

The active compounds may also be used successfully in theultra-low-volume process (ULV), it being possible to apply formulationscomprising over 95% by weight of active compound, or even to apply theactive compound without additives.

Various types of oils, wetters, adjuvants, herbicides, fungicides, otherpesticides, or bactericides may be added to the active compounds, ifappropriate just immediately prior to use (tank mix). These agents canbe admixed to the agents according to the invention, usually done in aweight ratio from 1:10 to 10:1.

The compounds I and II or the mixtures or the corresponding formulationsare applied by treating the harmful fungi or the plants, seeds, soils,areas, materials or spaces to be kept free from them with a fungicidallyeffective amount of the mixture or, in the case of separate application,of the compounds I and II. Application can be carried out before orafter infection by the harmful fungi.

The fungicidal action of the compound and the mixtures can bedemonstrated by the experiments below:

The active compounds, separately or jointly, were prepared as a stocksolution with 0.25% by weight of active compound in acetone or DMSO. 1%by weight of the emulsifier Uniperol® EL (wetting agent havingemulsifying and dispersing action based on ethoxylated alkylphenols) wasadded to this solution, and the solution was diluted with water to thedesired concentration.

Use Example—Protective Activity Against Rice Blast Caused by Pyriculariaoryzae

Leaves of rice seedlings of the cultivar “Tai-Nong 67”, which had beengrown in pots, were sprayed to runoff point with an aqueous suspensionhaving the concentration of active compounds stated below. The next day,the plants were inoculated with an aqueous spore suspension ofPyricularia oryzae. The test plants were then placed in climatizedchambers at 22-24° C. and 95-99% relative atmospheric humidity for 6days. The extent of the development of the infection on the leaves wasthen determined visually.

Evaluation was carried out by determining the infected leaf areas inpercent. These percentages were converted into efficacies.

The efficacy (E) is calculated as follows using Abbot's formula:E=(1−α/β)·100α corresponds to the fungicidal infection of the treated plants in % andβ corresponds to the fungicidal infection of the untreated (control)plants in %

An efficacy of 0 means that the infection level of the treated plantscorresponds to that of the untreated control plants; an efficacy of 100means that the treated plants were not infected.

The expected efficacies of the mixtures of active compounds aredetermined using Colby's formula [R. S. Colby, Weeds 15, 20-22 (1967)]and compared with the observed efficacies.

Colby's Formula:E=x+y−x·y/100

-   -   E expected efficacy, expressed in % of the untreated control,        when using the mixture of the active compounds A and B at the        concentrations a and b    -   x efficacy, expressed in % of the untreated control, when using        active compound A at the concentration a    -   y efficacy, expressed in % of the untreated control, when using        active compound B at the concentration b

The comparative compounds used were compounds A and B, known from thedimethomorph mixtures described in EP-A 988 790: TABLE A A

B

Individual active compounds Concentration of active Efficacy in %compound in the of the untreated Example Active compound spray liquor[ppm] control 1 control (untreated) — (90% infection) 2 I 1 11 3 IIa(dimethomorph) 4  0 0.25  0 4 IIb (flumorph) 4  0 0.25  0 5 Comparative1 11 compound A 6 Comparative 1 22 compound B

TABLE B Mixtures according to the invention Mixture of active compounds;Calculated Example concentration; mixing ratio Observed efficacyefficacy*) 7 I + IIa 78 11 1 + 4 ppm 1:4 8 I + IIa 56 11 1 + 0.25 ppm4:1 9 I + IIb 56 11 1 + 4 ppm 1:4 10 I + IIb 44 11 1 + 0.25 ppm 4:1*)efficacy calculated using Colby's formula

TABLE C Comparative experiments - mixtures known from EP-A 988 780Mixture of active compounds; Calculated Example concentration; mixingratio Observed efficacy efficacy*) 11 A + IIa 0 11 1 + 4 ppm 1:4 12 A +IIa 11 11 1 + 0.25 ppm 4:1 13 B + IIa 33 22 1 + 4 ppm 1:4 14 B + IIa 2222 1 + 0.25 ppm 4:1*)efficacy calculated using Colby's formula

The test results show that the mixtures according to the invention have,owing to strong synergism, considerably better activity against riceblast than the dimethomorph mixtures known from EP-A 988 780, althoughthe comparative compounds as individual active compounds have anactivity better than or comparable to that of compound I.

1. A fungicidal mixture for controlling rice pathogens, comprising 1)the triazolopyrimidine derivative of the formula,

and 2) an acryloylmorpholide of the formula II,

in which X is chlorine or fluorine, in a synergistically effectiveamount.
 2. A fungicidal mixture comprising the compound of the formula Iand the compounds of the formula II in a weight ratio of from 100:1 to1:100.
 3. A fungicidal mixture comprising, as acryloylmorpholide,dimethomorph of the formula IIa


4. A fungicidal composition comprising a liquid or solid carrier and amixture as claimed in claim
 1. 5. A method for controlling harmful fungiwhich are rice pathogens, which comprises treating the fungi, theirhabitat or the plants, the soil or the seeds to be protected againstfungal attack with an effective amount of the compound I and one of thecompounds II as set forth in claim
 1. 6. A method as claimed in claim 5,wherein the compounds I and II as set forth in claim 1 are appliedsimultaneously, that is jointly or separately, or in succession.
 7. Amethod as claimed in claim 5, wherein the mixture is applied in anamount of from 5 g/ha to 1500 g/ha.
 8. A method as claimed in claim 5 or6, wherein the mixture is applied in an amount of from 1 to 1000 g/100kg of seed.
 9. A method as claimed in claim 5, wherein the harmfulfungus Pyricularia oryzae is controlled.
 10. Seed, comprising themixture as claimed in claim 1, in an amount of from 1 to 1000 g/100 kg.11. The use of the compound I and the compound II as set forth in claim1 for preparing a composition suitable for controlling harmful fungi.